1. Field of the Invention
This invention lies in the field of methods for the manufacture of printed circuits, particularly in a multi-layered format, which employ photo-sensitive polymer systems that are cross-linkable by radiation.
2. Prior Art
Methods for the manufacture printed circuits using radiation cross-linkable photo-polymer systems have been proposed in the German Patent applications P 34 24 119.1 corresponding to USSN 749,588 filed June 27, 1985 and P 34 39 606.9 corresponding to USSN 762,513 filed Aug. 5, 1985 now U.S. Pat. No. 4,732,843, respectively. In the method described by German patent application P 34 24 119.1, cinnamic acid-epichlorohydrin-bisphenol A compounds which contain reactive hydroxy or hydroxymethylene groups at the bisphenol building block are employed as initial products for the polymerization in order to shorten the exposure time of radiation-sensitive enamels. The thermal loadability of products of these compounds is in fact extremely high, but such products when homopolymerized display only slight solubilities in standard organic solvents, such solubilities requiring an involved processing. Also, disadvantageous herein is a relatively low storage stability for the unexposed materials.
In the method described in patent application P 34 29606.9, polymer systems on an enamel base are employed both in order to achieve a low dielectric constant and in order to improve the constant temperature stability. In these polymer systems, linear fluoro-polymers having at least two reactive end groups per polymer molecule are employed as initial substances for conversion with radiation-sensitive substances. The conversion of the fluorinated initial substances and the linking thereof to the photo-active substances occurs in several method steps and in an involved way. Particularly due to the typically partly fluorinated solvent being employed, such method step combination also specifically requires involved processing technology in the subsequent multi-layer format.